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major reference

Self-condensation of aldehydes, the so-called aldol condensation, occurs readily, when catalyzed by bases, to give β-hydroxy aldehydes. The prototype of this reaction is the conversion of acetaldehyde to β-hydroxybutyraldehyde, or aldol. The first step of this reaction is the production of an…

ketones

…undergo aldol reactions (also called aldol condensation) by the use of certain techniques. The reaction is often used to close rings, in which case one carbon provides the carbonyl group and another provides the carbon with an α-hydrogen. An example is the synthesis of 2-cyclohexenone. In this example, the aldol…